Thursday, 15 December 2016

This stunning Antarctic lake is buried in ice. And that could be bad news

Atop the ice sheet covering the Arctic island of Greenland, you now see dramatic melting in the summer. It forms lakes, rivers and even dangerous "moulins" in the ice where rivers suddenly plunge into the thick ice sheet, carrying water deep below.

East Antarctica is supposed to be different. It is extremely remote and cold. It doesn't see such warm temperatures in the summer - yet - and so its ice tends to remain more pristine.

"Many people refer to East Antarctica as being too cold for significant melt," says Jan Lenaerts, a glaciologist with the Utrecht University in the Netherlands.

"I mean there's marginal melt in summer, but there's not a lot."

That's the common wisdom, at least, but it is challenged in a new study in Nature Climate Change, by Lenaerts and his colleagues from universities in the Netherlands, Belgium and Germany. They do so based on research they conducted atop the very large Roi Baudouin ice shelf in East Antarctica, which floats atop the ocean, and where they found a very Greenland-like situation in early 2016.

The researchers had traveled to investigate what had been described as a nearly 2-mile-wide "crater" in the shelf, glimpsed by satellite, which some sources believed had been caused by a meteorite. To the contrary, they found that it was a large, 10 foot deep, icy lake bed. In its center, meanwhile, were multiple rivers and three moulins that carried water deep down into the floating ice shelf.

And even this, perhaps, was not the most dramatic finding. The researchers also drilled through the ice and found what they called "englacial" lakes, sandwiched between the surface of the ice shelf and its base, which is in contact with the ocean beneath it. They found 55 lakes in total on or in the ice shelf, and a number of them were in this buried, englacial format.

This meant that the ice shelf is anything but solid - it had many large pockets of weakness throughout its structure, suggesting a greater potential vulnerability to collapse through a process called "hydrofracturing," especially if lake formation continues or increases. That's bad news because when ice shelves fall apart, the glacial ice behind them flows more rapidly to the ocean, raising sea levels.
But why was all this happening, and here?

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